The invention relates to an automatic forming machine, in particular an eccentric forging or crank press, for hot forging workpieces which are conveyed stepwise through a forging region, having a driven eccentric shaft on which there is mounted a connecting rod connected to the tool carriage, which can be moved up and down and with which there is associated an irregular drive having a stationary, internally toothed hollow gear meshing with a planet pinion gear.
DE-AS 2 061 043 discloses a die forging press (eccentric press, wedge press or the like) having automatic workpiece transport, in which walking beams and an automatic drive associated therewith are provided for transporting the workpiece from die to die. The walking beams receive the workpiece between them and are provided with suitable gear systems which enable raising and lowering, closing and opening and longitudinal movement of the walking beams.
The result is that the maximum production rates per unit of time depend on the minimum cycle time, which in the case of a fully automatic forming machine is generally determined by the time for transporting the forged pieces from one die to the next. In addition to transporting the forged pieces, during this time the following functions (handling) also take place: press stroke up and down, discharge of the forged pieces by mechanical dischargers above and below, cleaning, cooling and application of lubricant to the dies. In the case of cold and semi-hot metal forming of the forged pieces, the press stroke is slowed down to the extent necessary for the transporting time. Thus, speeds (cycle time) of 20 to 30 rpm can be used there without disadvantages for the forged pieces. In contrast, such speeds are not possible with hot forging, since in the event of excessively low speeds the die contact times become too high, with the consequence of an abruptly reduced service life of the dies. For this reason, with hot forging in practice eccentric forging presses are operated--depending on the size of the press--at speeds between 50 and 70 rpm. However, this means that taking into account the required cycle times continuous operation is not possible and in general even fully automatic forming machines (eccentric forging or crank press) have to be used in switched operation. This necessitates, after each revolution of the eccentric shaft, coupling and deceleration. In automatic operation with walking beam systems, minimum cycle times of approximately 2.5 to 3.5 seconds are then possible.